<?php

/*************************************************************************
 *                                                                       *
* class.html2text.inc                                                   *
*                                                                       *
*************************************************************************
*                                                                       *
* Converts HTML to formatted plain text                                 *
*                                                                       *
* Copyright (c) 2005-2007 Jon Abernathy <jon@chuggnutt.com>             *
* All rights reserved.                                                  *
*                                                                       *
* This script is free software; you can redistribute it and/or modify   *
* it under the terms of the GNU General Public License as published by  *
* the Free Software Foundation; either version 2 of the License, or     *
* (at your option) any later version.                                   *
*                                                                       *
* The GNU General Public License can be found at                        *
* http://www.gnu.org/copyleft/gpl.html.                                 *
*                                                                       *
* This script is distributed in the hope that it will be useful,        *
* but WITHOUT ANY WARRANTY; without even the implied warranty of        *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the          *
* GNU General Public License for more details.                          *
*                                                                       *
* Author(s): Jon Abernathy <jon@chuggnutt.com>                          *
*                                                                       *
* Last modified: 08/08/07                                               *
*                                                                       *
*************************************************************************/


/**
 *  Takes HTML and converts it to formatted, plain text.
*
*  Thanks to Alexander Krug (http://www.krugar.de/) to pointing out and
*  correcting an error in the regexp search array. Fixed 7/30/03.
*
*  Updated set_html() function's file reading mechanism, 9/25/03.
*
*  Thanks to Joss Sanglier (http://www.dancingbear.co.uk/) for adding
*  several more HTML entity codes to the $search and $replace arrays.
*  Updated 11/7/03.
*
*  Thanks to Darius Kasperavicius (http://www.dar.dar.lt/) for
*  suggesting the addition of $allowed_tags and its supporting function
*  (which I slightly modified). Updated 3/12/04.
*
*  Thanks to Justin Dearing for pointing out that a replacement for the
*  <TH> tag was missing, and suggesting an appropriate fix.
*  Updated 8/25/04.
*
*  Thanks to Mathieu Collas (http://www.myefarm.com/) for finding a
*  display/formatting bug in the _build_link_list() function: email
*  readers would show the left bracket and number ("[1") as part of the
*  rendered email address.
*  Updated 12/16/04.
*
*  Thanks to Wojciech Bajon (http://histeria.pl/) for submitting code
*  to handle relative links, which I hadn't considered. I modified his
*  code a bit to handle normal HTTP links and MAILTO links. Also for
*  suggesting three additional HTML entity codes to search for.
*  Updated 03/02/05.
*
*  Thanks to Jacob Chandler for pointing out another link condition
*  for the _build_link_list() function: "https".
*  Updated 04/06/05.
*
*  Thanks to Marc Bertrand (http://www.dresdensky.com/) for
*  suggesting a revision to the word wrapping functionality; if you
*  specify a $width of 0 or less, word wrapping will be ignored.
*  Updated 11/02/06.
*
*  *** Big housecleaning updates below:
*
*  Thanks to Colin Brown (http://www.sparkdriver.co.uk/) for
*  suggesting the fix to handle </li> and blank lines (whitespace).
*  Christian Basedau (http://www.movetheweb.de/) also suggested the
*  blank lines fix.
*
*  Special thanks to Marcus Bointon (http://www.synchromedia.co.uk/),
*  Christian Basedau, Norbert Laposa (http://ln5.co.uk/),
*  Bas van de Weijer, and Marijn van Butselaar
*  for pointing out my glaring error in the <th> handling. Marcus also
*  supplied a host of fixes.
*
*  Thanks to Jeffrey Silverman (http://www.newtnotes.com/) for pointing
*  out that extra spaces should be compressed--a problem addressed with
*  Marcus Bointon's fixes but that I had not yet incorporated.
*
*	Thanks to Daniel Schledermann (http://www.typoconsult.dk/) for
*  suggesting a valuable fix with <a> tag handling.
*
*  Thanks to Wojciech Bajon (again!) for suggesting fixes and additions,
*  including the <a> tag handling that Daniel Schledermann pointed
*  out but that I had not yet incorporated. I haven't (yet)
*  incorporated all of Wojciech's changes, though I may at some
*  future time.
*
*  *** End of the housecleaning updates. Updated 08/08/07.
*
*  @author Jon Abernathy <jon@chuggnutt.com>
*  @version 1.0.0
*  @since PHP 4.0.2
*/
class html2text
{

	/**
	 *  Contains the HTML content to convert.
	 *
	 *  @var string $html
	 *  @access public
	 */
	var $html;

	/**
	 *  Contains the converted, formatted text.
	 *
	 *  @var string $text
	 *  @access public
	 */
	var $text;

	/**
	 *  Maximum width of the formatted text, in columns.
	 *
	 *  Set this value to 0 (or less) to ignore word wrapping
	 *  and not constrain text to a fixed-width column.
	 *
	 *  @var integer $width
	 *  @access public
	 */
	var $width = 70;

	/**
	 *  List of preg* regular expression patterns to search for,
	 *  used in conjunction with $replace.
	 *
	 *  @var array $search
	 *  @access public
	 *  @see $replace
	 */
	var $search = array(
        "/\r/",                                  // Non-legal carriage return
        "/[\n\t]+/",                             // Newlines and tabs
        '/[ ]{2,}/',                             // Runs of spaces, pre-handling
        '/<script[^>]*>.*?<\/script>/i',         // <script>s -- which strip_tags supposedly has problems with
        '/<style[^>]*>.*?<\/style>/i',           // <style>s -- which strip_tags supposedly has problems with
	//'/<!-- .* -->/',                         // Comments -- which strip_tags might have problem a with
        '/<h[123][^>]*>(.*?)<\/h[123]>/ie',      // H1 - H3
        '/<h[456][^>]*>(.*?)<\/h[456]>/ie',      // H4 - H6
        '/<p[^>]*>/i',                           // <P>
        '/<br[^>]*>/i',                          // <br>
        '/<b[^>]*>(.*?)<\/b>/ie',                // <b>
        '/<strong[^>]*>(.*?)<\/strong>/ie',      // <strong>
        '/<i[^>]*>(.*?)<\/i>/i',                 // <i>
        '/<em[^>]*>(.*?)<\/em>/i',               // <em>
        '/(<ul[^>]*>|<\/ul>)/i',                 // <ul> and </ul>
        '/(<ol[^>]*>|<\/ol>)/i',                 // <ol> and </ol>
        '/<li[^>]*>(.*?)<\/li>/i',               // <li> and </li>
        '/<li[^>]*>/i',                          // <li>
        '/<a [^>]*href="([^"]+)"[^>]*>(.*?)<\/a>/ie',
	// <a href="">
        '/<hr[^>]*>/i',                          // <hr>
        '/(<table[^>]*>|<\/table>)/i',           // <table> and </table>
        '/(<tr[^>]*>|<\/tr>)/i',                 // <tr> and </tr>
        '/<td[^>]*>(.*?)<\/td>/i',               // <td> and </td>
        '/<th[^>]*>(.*?)<\/th>/ie',              // <th> and </th>
        '/&(nbsp|#160);/i',                      // Non-breaking space
        '/&(quot|rdquo|ldquo|#8220|#8221|#147|#148);/i',
	// Double quotes
        '/&(apos|rsquo|lsquo|#8216|#8217);/i',   // Single quotes
        '/&gt;/i',                               // Greater-than
        '/&lt;/i',                               // Less-than
        '/&(amp|#38);/i',                        // Ampersand
        '/&(copy|#169);/i',                      // Copyright
        '/&(trade|#8482|#153);/i',               // Trademark
        '/&(reg|#174);/i',                       // Registered
        '/&(mdash|#151|#8212);/i',               // mdash
        '/&(ndash|minus|#8211|#8722);/i',        // ndash
        '/&(bull|#149|#8226);/i',                // Bullet
        '/&(pound|#163);/i',                     // Pound sign
        '/&(euro|#8364);/i',                     // Euro sign
        '/&[^&;]+;/i',                           // Unknown/unhandled entities
        '/[ ]{2,}/'                              // Runs of spaces, post-handling
	);

	/**
	 *  List of pattern replacements corresponding to patterns searched.
	 *
	 *  @var array $replace
	 *  @access public
	 *  @see $search
	 */
	var $replace = array(
        '',                                     // Non-legal carriage return
        ' ',                                    // Newlines and tabs
        ' ',                                    // Runs of spaces, pre-handling
        '',                                     // <script>s -- which strip_tags supposedly has problems with
        '',                                     // <style>s -- which strip_tags supposedly has problems with
	//'',                                     // Comments -- which strip_tags might have problem a with
        "strtoupper(\"\n\n\\1\n\n\")",          // H1 - H3
        "ucwords(\"\n\n\\1\n\n\")",             // H4 - H6
        "\n\n\t",                               // <P>
        "\n",                                   // <br>
        'strtoupper("\\1")',                    // <b>
        'strtoupper("\\1")',                    // <strong>
        '_\\1_',                                // <i>
        '_\\1_',                                // <em>
        "\n\n",                                 // <ul> and </ul>
        "\n\n",                                 // <ol> and </ol>
        "\t* \\1\n",                            // <li> and </li>
        "\n\t* ",                               // <li>
        '$this->_build_link_list("\\1", "\\2")',
	// <a href="">
        "\n-------------------------\n",        // <hr>
        "\n\n",                                 // <table> and </table>
        "\n",                                   // <tr> and </tr>
        "\t\t\\1\n",                            // <td> and </td>
        "strtoupper(\"\t\t\\1\n\")",            // <th> and </th>
        ' ',                                    // Non-breaking space
        '"',                                    // Double quotes
        "'",                                    // Single quotes
        '>',
        '<',
        '&',
        '(c)',
        '(tm)',
        '(R)',
        '--',
        '-',
        '*',
        '\A3',
        'EUR',                                  // Euro sign. \80 ?
        '',                                     // Unknown/unhandled entities
        ' '                                     // Runs of spaces, post-handling
	);

	/**
	 *  Contains a list of HTML tags to allow in the resulting text.
	 *
	 *  @var string $allowed_tags
	 *  @access public
	 *  @see set_allowed_tags()
	 */
	var $allowed_tags = '';

	/**
	 *  Contains the base URL that relative links should resolve to.
	 *
	 *  @var string $url
	 *  @access public
	 */
	var $url;

	/**
	 *  Indicates whether content in the $html variable has been converted yet.
	 *
	 *  @var boolean $_converted
	 *  @access private
	 *  @see $html, $text
	 */
	var $_converted = false;

	/**
	 *  Contains URL addresses from links to be rendered in plain text.
	 *
	 *  @var string $_link_list
	 *  @access private
	 *  @see _build_link_list()
	 */
	var $_link_list = '';

	/**
	 *  Number of valid links detected in the text, used for plain text
	 *  display (rendered similar to footnotes).
	 *
	 *  @var integer $_link_count
	 *  @access private
	 *  @see _build_link_list()
	 */
	var $_link_count = 0;

	/**
	 *  Constructor.
	 *
	 *  If the HTML source string (or file) is supplied, the class
	 *  will instantiate with that source propagated, all that has
	 *  to be done it to call get_text().
	 *
	 *  @param string $source HTML content
	 *  @param boolean $from_file Indicates $source is a file to pull content from
	 *  @access public
	 *  @return void
	 */
	function html2text( $source = '', $from_file = false )
	{
		if ( !empty($source) ) {
			$this->set_html($source, $from_file);
		}
		$this->set_base_url();
	}

	/**
	 *  Loads source HTML into memory, either from $source string or a file.
	 *
	 *  @param string $source HTML content
	 *  @param boolean $from_file Indicates $source is a file to pull content from
	 *  @access public
	 *  @return void
	 */
	function set_html( $source, $from_file = false )
	{
		$this->html = $source;

		if ( $from_file && file_exists($source) ) {
			$fp = fopen($source, 'r');
			$this->html = fread($fp, filesize($source));
			fclose($fp);
		}

		$this->_converted = false;
	}

	/**
	 *  Returns the text, converted from HTML.
	 *
	 *  @access public
	 *  @return string
	 */
	function get_text()
	{
		if ( !$this->_converted ) {
			$this->_convert();
		}

		return $this->text;
	}

	/**
	 *  Prints the text, converted from HTML.
	 *
	 *  @access public
	 *  @return void
	 */
	function print_text()
	{
		print $this->get_text();
	}

	/**
	 *  Alias to print_text(), operates identically.
	 *
	 *  @access public
	 *  @return void
	 *  @see print_text()
	 */
	function p()
	{
		print $this->get_text();
	}

	/**
	 *  Sets the allowed HTML tags to pass through to the resulting text.
	 *
	 *  Tags should be in the form "<p>", with no corresponding closing tag.
	 *
	 *  @access public
	 *  @return void
	 */
	function set_allowed_tags( $allowed_tags = '' )
	{
		if ( !empty($allowed_tags) ) {
			$this->allowed_tags = $allowed_tags;
		}
	}

	/**
	 *  Sets a base URL to handle relative links.
	 *
	 *  @access public
	 *  @return void
	 */
	function set_base_url( $url = '' )
	{
		if ( empty($url) ) {
			if ( !empty($_SERVER['HTTP_HOST']) ) {
				$this->url = 'http://' . $_SERVER['HTTP_HOST'];
			} else {
				$this->url = '';
			}
		} else {
			// Strip any trailing slashes for consistency (relative
			// URLs may already start with a slash like "/file.html")
			if ( substr($url, -1) == '/' ) {
				$url = substr($url, 0, -1);
			}
			$this->url = $url;
		}
	}

	/**
	 *  Workhorse function that does actual conversion.
	 *
	 *  First performs custom tag replacement specified by $search and
	 *  $replace arrays. Then strips any remaining HTML tags, reduces whitespace
	 *  and newlines to a readable format, and word wraps the text to
	 *  $width characters.
	 *
	 *  @access private
	 *  @return void
	 */
	function _convert()
	{
		// Variables used for building the link list
		$this->_link_count = 0;
		$this->_link_list = '';

		$text = trim(stripslashes($this->html));

		// Run our defined search-and-replace
		$text = preg_replace($this->search, $this->replace, $text);

		// Strip any other HTML tags
		$text = strip_tags($text, $this->allowed_tags);

		// Bring down number of empty lines to 2 max
		$text = preg_replace("/\n\s+\n/", "\n\n", $text);
		$text = preg_replace("/[\n]{3,}/", "\n\n", $text);

		// Add link list
		if ( !empty($this->_link_list) ) {
			$text .= "\n\nLinks:\n------\n" . $this->_link_list;
		}

		// Wrap the text to a readable format
		// for PHP versions >= 4.0.2. Default width is 75
		// If width is 0 or less, don't wrap the text.
		if ( $this->width > 0 ) {
			$text = wordwrap($text, $this->width);
		}

		$this->text = $text;

		$this->_converted = true;
	}

	/**
	 *  Helper function called by preg_replace() on link replacement.
	 *
	 *  Maintains an internal list of links to be displayed at the end of the
	 *  text, with numeric indices to the original point in the text they
	 *  appeared. Also makes an effort at identifying and handling absolute
	 *  and relative links.
	 *
	 *  @param string $link URL of the link
	 *  @param string $display Part of the text to associate number with
	 *  @access private
	 *  @return string
	 */
	function _build_link_list( $link, $display )
	{
		if ( substr($link, 0, 7) == 'http://' || substr($link, 0, 8) == 'https://' ||
		substr($link, 0, 7) == 'mailto:' ) {
			$this->_link_count++;
			$this->_link_list .= "[" . $this->_link_count . "] $link\n";
			$additional = ' [' . $this->_link_count . ']';
		} elseif ( substr($link, 0, 11) == 'javascript:' ) {
			// Don't count the link; ignore it
			$additional = '';
			// what about href="#anchor" ?
		} else {
			$this->_link_count++;
			$this->_link_list .= "[" . $this->_link_count . "] " . $this->url;
			if ( substr($link, 0, 1) != '/' ) {
				$this->_link_list .= '/';
			}
			$this->_link_list .= "$link\n";
			$additional = ' [' . $this->_link_count . ']';
		}

		return $display . $additional;
	}

}

?>